As the number of wireless cellular data communication devices continues to increase and as their data capabilities continue to be more and more heavily used, the demands on available infrastructure and frequencies continue to increase. The addition of infrastructure to meet demand is costly, and is becoming more and more difficult as unoccupied space suitable for placement of base stations diminishes. In addition, as saturation of available wireless communication frequencies approaches, addition of infrastructure approaches a point of ineffectiveness.
In order to support the growing demand for data communication services, therefore, network operators are turning more and more toward increasing the efficiency of their operations. One mechanism that has shown promise is the use of active antenna systems (AAS) and, in particular, vertical sectorization (VS). Active antenna systems are radio embedded base station antennas that integrate conventional base station radiofrequency (RF) components with the antenna elements. Such an approach has the direct effect of eliminating RF power losses in RF feeder cables and minimizing the number of hardware items to be implemented. One additional significant benefit of AAS is the ability to control antenna parameters electronically, such as by changing azimuth and elevation patterns and steering radiated beams vertically and horizontally by remote electrical tilt (RET). Tilt control provided by AAS may be accomplished on a carrier, frequency, or service basis allowing flexibility for advanced network planning features such as vertical sectorization.
Vertical sectorization increases the number of cells beyond the number provided by conventional mechanisms, generally enabling two cells in the vertical plane per conventional cell sector. In general, the outer sector is optimized for cell coverage and inner sector is adjusted to maximize cell capacity, creating two dedicated cells effectively doubles available resources over the area as a whole, significantly improving performance. Vertical sectorization also allows the direction of dedicated resources to sector edges, thus improving outer sector coverage. In addition, vertical sectorization can lower deployment and operational costs to operators by reducing the number of base station sites required.